S is for sheep
Bighorn Sheep at Waterton National Park, Alberta, Canada.
Sigma 150-500 mm lens
Bighorn sheep (Ovis canadensis)3 is a species of sheep in North America4 with large horns. The horns can weigh up to 30 pounds (14 kg), while the sheep themselves weigh up to 300 pounds (140 kg).5 Recent genetic testing indicates that there are three distinct subspecies of Ovis canadensis, one of which is endangered: Ovis canadensis sierrae.
The bighorn sheep originally crossed over the Bering land bridge from Siberia: the population in North America peaked in the millions, and the bighorn sheep entered into the mythology of Native Americans. However, by 1900 the population had crashed to several thousand. Conservation efforts (in part, by the Boy Scouts) have restored the population.